Brushless Motors

As well as the range of motors listed below, other models and spare parts - brush mechanisms, armatures, fans, etc. are also available ex-stock.

Ross Brown Sales Pty Ltd always recommend that our electric motors be installed by or under the supervision of a licenced electrician. Click Here to download the Operating and Installation Instructions for Lamb Bypass Vacuum Motors.

Proper ventilation of bypass vacuum motors in cleaners and other appliances is critical to attaining their design life. This is a critical design consideration in the application of Lamb bypass vacuum motors. This discussion is not intended to be critical of any particular appliance. Rather, it puts forth considerations to be taken into account in the application of Lamb bypass vacuum motors in appliances.

The most common problem encountered is recirculation of the cooling air where there is not a positive separation between the cooling air inlet and discharge areas. By using heated air to cool the motor, it can run at elevated temperatures and thus can shorten the life expectancy of the unit. While the appliance may pass temperature tests at agencies with this condition, the elevated temperature caused by the recirculation can put the motor at risk of premature failure.

Care must be taken to prevent recirculation of cooling air. Many effective methods have been employed to prevent recirculation of ventilation air. These include using foam rings and other sealants between the vent fan housing and the appliance body, having the motor extend outside the unit housing, etc. It is important to ensure that only cool, ambient air is used for motor cooling. The discharge air should be directed away from the cooling air inlet to ensure that outside ambient air only is used for cooling.

Another common problem is the result of restricted inlet or discharge area for the ventilation air. Lamb recommends that a minimum of 3 square inches of area be allowed for both the inlet and discharge of the cooling air. If this area is not provided, the motor temperature can be effected to the point that it will run hotter than normal and can result in premature failure.

The appliance should be installed or used in an area where the ambient temperature in not elevated to high levels. For a central vacuum cleaner, such areas as small closets, attics, garages can have very high ambient temperatures that will create problems for the motors in operation.

Continued operation of the vacuum motor at very high temperatures can lead to premature failure. One of the most common problems seen is bar movement of the commutator. Commutator construction varies but most of the units that Lamb uses have the bars held in place with a moulding compound. These commutators are very durable and have been highly reliable when the operating temperatures of the motors are within agency limitations.

However, high ambient temperature can cause a bar on the commutator to move slightly. When this happens the carbon brush can jump slightly on each revolution of the armature. This causes excessive arcing at the brushes and this leads it turn to increased temperature. Once this starts, the motor generally fails prematurely. Other potential problems of high temperature motor operation is increased dusting of the brushes (also a factor of raised commutator bars) and the possibility of armature shorts.

Operation of Vacuum Motors in Air Series

It is possible to connect two vacuum motors in air series by connecting they discharge of the first motor to the inlet of the second motor to increase the overall vacuum level in a cleaning machine. We have a number of customers that utilise motors in this manner in various types of equipment.

There are potential problems associated with the air series application of motors as it produces a severe thermal condition on the second motor. The discharge air from the first motor is quite warm and when it is ducted to the second motor, the heated air increases further in temperature due to the compression of the air in the vacuum system.

The high temperatures can have an adverse effect on the bearing system of the second motor. In addition, the high temperatures coupled with the increased pressure in the second motor can cause the grease to be forced out of the ball bearing at the bottom (fan end) of the second motor.

Depending on the effective operating orifice of the vacuum system, enough heat can be generated to cause deformation of the fan system that can lead to a fan strike or locked rotor condition.

Another problem is the electrical current required to operate the air series vacuum system. Special wiring assemblies and circuits may be necessary to carry the high current level when operating two motors in air series.

When two like motors are connected in air series, the sealed vacuum level will increase by approximately 60% from that of a single motor. Airflow at a wide open condition does not appreciably increase by operating two vacuum motors in air series.

Another problem frequently seen in air series applications is that adequate cooling air is not provided for the first or lower motor. Both motors must receive cooling air directly from outside the motor enclosure and there must not be any recirculation of motor cooling air. If the motors are not properly cooled, severe thermal problems can develop in the motors.

Applications using vacuum motors connected in air series should be thoroughly tested to ensure the integrity of your design. There are potential problems with this type of application as noted above and these must be fully understood. Air series installations might have an adverse effect on the life of the motors and the reliability of your equipment.

Carbon Brush Consumption

In the process of commutation, the carbon of the brushes is consumed. Some of this material is consumed in the maintenance of the film of carbon on the commutator. Most of the carbon is abraded away and escapes in the air stream. When a motor is running well, the dusting is minimal because consumption per hour is low, and the concentration of the dust in the air stream at any time is minimal.

When a motor is commutating poorly, carbon is being consumed at a faster rate. This could be as the film on the commutator is built up and then torn down as the resins and binders are cooked out of the brush by excessive heating. It also could be as the result of friction as could be the case if the comm had a poor finish or there was movement of a bar. In these cases, more carbon is being used per hour and it is discharged into the ventilation air stream.

In a typical central vacuum system, there is generally a lot of static electricity built up in the PVC pipe by the movement of air and debris through the system. The pipes attract the carbon dust that has been discharged into the air stream and thus the coating on the pipes. Carbon dust is a natural by product of running a vacuum motor. It will always be there by nature of the machine.

There is a growing trend in the European market to place filters on the discharge air to trap carbon dust and other dust in the air going through the vent system. This could prevent a large portion of the carbon dust from escaping from the power unit.

If the area where the unit is installed is very dry, i.e. high altitude, low humidity, etc., this could contribute to the dusting on the pipes. We have seen a number of installations in Scandinavia where there was a lot of carbon dust on the pipes, especially during the Winter.

Another idea that could assist would be to wrap the pipes in the area of the power unit with bare copper wire and connecting it to ground. This would discharge the static charge in the pipes and reduce the attraction point for the airborne carbon dust. However, in this case, if the static charge is removed from the pipe, the carbon dust will be free to go anywhere the discharge air goes and will not be collected on the pipe.

It is important to check the operating condition of the vacuum motor if excessive dusting is observed as this condition could be the cause of some other mechanical or electrical problem.

Dusting of the carbon brush material is normal for a vacuum motor. If there is very high static charge levels in the pipe, the carbon dust can collect more quickly on the pipes as well as on the power unit. The same dusting is present with canister and other vacuum motors. However, since there is not the build-up of static charges as in a central vacuum cleaner with plastic duct pipes, the carbon dust is discharged back into the air in the area being vacuumed.

Changing Carbon Brushes

The following steps should be followed when changing the carbon brushes on Lamb vacuum motors. For best results, always use original Lamb replacement parts.

1. Disconnect motor from the power source and remove vent fan cover if the unit is a bypass design. 2. Insert a standard blade screw driver between the top of the brush mechanism and the brush lead wire clip and gently tap the screw driver handle until the clip touches the commutator. Some models have blade terminals on the brush holder. For these units, remove the connector from the blade terminal. 3. Remove the brush clamp screws with a Phillips screw driver. 4. Once the brush mechanism is free, generally the brush clip can be removed the rest of the way by hand. 5. To install new brush mechanism, first insert the brush clip into the end of the brush mechanism between the nylon insulator and the brass and push in straight by hand. Then use needle nose or standard flat blade pliers to gently seat the clip. For the units with the blade terminal, push the connector on to the terminal. 6. Insert the locator tab on the bottom of the brush mechanism into the corresponding hole on the top of the commutator end bracket and secure the mechanism with the brush clamp and the screws that were earlier removed. 7. To properly seat the carbon brush on the commutator, operate the motor at half voltage for about 30 minutes and then operate the motor at full voltage for an additional 30 minutes.